Method for preparation of homogenous catalyst for selective 1-hexene production

ABSTRACT

A method for preparing a homogenous catalyst for the production of linear alpha olefins includes: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel for a period of time of 1 hour to 90 days; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel for a period of time of 1 hour to 90 days; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst pre-formation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the homogenous catalyst.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Application of PCT/IB2017/058301, filed Dec. 21, 2017, which claims the benefit of U.S. Provisional Application No. 62/440,559, filed Dec. 30, 2016, both of which are incorporated by reference in their entirety herein.

BACKGROUND

Linear alpha olefins (LAOs) are olefins with a chemical formula C_(x)H_(2x), distinguished from other mono-olefins with a similar molecular formula by linearity of the hydrocarbon chain and the position of the double bond at the primary or alpha position. Linear alpha olefins comprise a class of industrially important alpha-olefins, including 1-butene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and higher blends of C₂₀-C₂₄, C₂₄-C₃₀, and C₂₀-C₃₀ olefins. Linear alpha-olefins (LAOs), for example those with four to 30 carbon atoms, are compounds which are, for example, widely used and required in large quantities as comonomers for modifying the properties of polyolefins or as a starting material for the production of plasticizers, household cleansers, flotation agents, emulsifiers, drinking fluids, surface-active substances, synthetic oils, putties, sealants, and the like. Existing processes for the production of linear alpha olefins typically rely on the oligomerization of ethylene.

Methods for the oligomerization of ethylene using various catalyst compositions are known. Typically, if very unspecific catalysts are used, a broad product distribution is obtained from C4 to higher olefins and even polymeric materials. Recently, catalyst compositions for the oligomerization of ethylene have been developed which are more specific to, for example, trimerization or tetramerization, thus resulting in a narrower product distribution, but still also producing higher linear alpha-olefins and polymeric materials. Catalyst systems and processes for the oligomerization of ethylene, in particular for the selective trimerization of ethylene to 1-hexene and/or the tetramerization to 1-octene are widely known.

The selective ethylene trimerization catalysts disclosed so far in scientific and patent literature generally have to cope with the following challenges: very narrow or unsuitable window of operability of the catalyst system in terms of process conditions such as temperature, pressure, residence time, catalyst concentration, and the like.

Selective 1-Hexene production via on-purpose linear alpha olefin technology utilizes a homogenous catalyst formed of four components. Previous catalyst compositions comprising, for example, a chromium compound, a ligand, a modifier and an activator show several disadvantages. First, some of the catalyst's components are poorly soluble in the aromatic solvents of the process. This is especially true for the modifier. Second, all catalyst constituents need to be meticulously metered into the reactor to adjust the productivity very precisely and avoid thermal runaways. This prohibits the use of slurry systems or any system for handling solids. Instead, the catalyst components should be introduced into the reactor by dosing pumps. Third, for high productivities and high selectivity, the catalyst composition needs to be precisely defined in terms of total chromium concentration and particularly regarding the molar ratios of ligand/chromium, aluminum/chromium and modifier/chromium. Fourth, preparation of the entire homogenous catalyst, including all four components, is not feasible in a technical environment due to the degradation of the catalyst on a timescale of equal or greater than approximately one day. This degradation results in deteriorating activity and increased wax/polymer formation. Further, ingress of moisture or air from the environment into the storage equipment during unloading of catalyst components should be prevented. The catalyst components are mixed and then immediately transferred to the oligomerization reactor to avoid decomposition of the catalyst system leading to deteriorating activities and side product formation.

Due to the catalyst's short shelf life, it is necessary to prepare the homogenous catalyst directly before injection into reactors with minimum transportation time. The preparation of the homogenous catalyst must assure base line catalyst activity in the reactor.

Thus, there is a need for a method of preparing a homogenous catalyst that assures baseline catalyst activity in a reactor and to provide a process for preparing a catalyst composition for oligomerization of ethylene to overcome the problems associated with the catalyst's short shelf life and as described herein and create a new method of creating a usable homogenous catalyst.

SUMMARY

Disclosed, in various embodiments, is a method of preparing a homogenous catalyst for the production of linear alpha olefins.

A method for preparing a homogenous catalyst for the production of linear alpha olefins comprises: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel for a period of time of 1 hour to 90 days; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel for a period of time of 1 hour to 90 days; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst pre-formation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the homogenous catalyst.

These and other features and characteristics are more particularly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings wherein like elements are numbered alike and which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

FIG. 1 is a block flow diagram for catalyst preparation and dosing.

FIG. 2 is a schematic representation of a catalyst preformation unit.

DETAILED DESCRIPTION

Disclosed herein is a method that is able to overcome the problem of short catalyst shelf life by preparing a homogenous catalyst for use in on-purpose linear alpha olefin technology in a two-step process. Accordingly, described herein is a system and method of preparing catalyst compositions for the oligomerization of ethylene to produce 1-hexene that results in catalyst compositions with a longer useful life (i.e., a longer shelf life). In the method disclosed herein, a first pre-catalyst solution and a second pre-catalyst solution can be prepared and stored in separate vessels for up to 90 days. It was surprisingly discovered that the pre-catalyst solutions could be stored for a period of time rather than being prepared immediately before injection into the reactor to form the homogenous catalyst. During storage, the pre-catalyst solutions can be continuously recirculated, for examples, through a pump and cooler. A temperature of the stream can be maintained at 10-50° C., for example, 15-25° C. Recirculation and temperature maintenance can assist in cooling and maintaining homogeneity of the stored pre-catalyst solutions.

The method for preparation of a homogenous catalyst can employ three solid components and a liquid component in a two-step process. The homogeneous catalyst composition can include, for example, (i) a chromium source, (ii) a ligand, (iii) a modifier, (iv) a solvent, and (v) an organoaluminum compound. The first step can include preparation of two pre-catalyst solutions. The first pre-catalyst solution can comprise a modifier and an organoaluminum compound in a first solvent. The second pre-catalyst solution can include a ligand and a chromium source in a second solvent. The second step can include mixing the two pre-catalyst solutions to form the homogenous catalyst. The homogenous catalyst can be directly injected into the reactor, e.g., an oligomerization reactor or can be injected into a solvent feed stream, e.g., a hydrocarbon feed stream, upstream the reactor. Injection into the feed stream can allow for more even distribution of the homogenous catalyst inside the reactor.

1-Hexene is commonly manufactured by two general routes: (i) full-range processes via the oligomerization of ethylene and (ii) on-purpose technology. A minor route to 1-hexene, used commercially on smaller scales, is the dehydration of hexanol. Prior to the 1970s, 1-hexene was also manufactured by the thermal cracking of waxes. Linear internal hexenes were manufactured by chlorination/dehydrochlorination of linear paraffins.

“Ethylene oligomerization” combines ethylene molecules to produce linear alpha-olefins of various chain lengths with an even number of carbon atoms. This approach results in a distribution of alpha-olefins. Oligomerization of ethylene can produce 1-hexene.

Fischer-Tropsch synthesis to make fuels from synthesis gas derived from coal can recover 1-hexene from the aforementioned fuel streams, where the initial 1-hexene concentration cut can be 60% in a narrow distillation, with the remainder being vinylidenes, linear and branched internal olefins, linear and branched paraffins, alcohols, aldehydes, carboxylic acids, and aromatic compounds. The trimerization of ethylene by homogeneous catalysts has been demonstrated.

There are a wide range of applications for linear alpha olefins. The lower carbon numbers, 1-butene, 1-hexene and 1-octene can be used as comonomers in the production of polyethylene. High density polyethylene (HDPE) and linear low density polyethylene (LLDPE) can use approximately 2-4% and 8-10% of comonomers, respectively.

Another use of C₄-C₈ linear alpha olefins, can be for production of linear aldehyde via oxo synthesis (hydroformylation) for later production of short-chain fatty acid, a carboxylic acid, by oxidation of an intermediate aldehyde, or linear alcohols for plasticizer application by hydrogenation of the aldehyde.

An application of 1-decene is in making polyalphaolefin synthetic lubricant base stock (PAO) and to make surfactants in a blend with higher linear alpha olefins.

C₁₀-C₁₄ linear alpha olefins can be used in making surfactants for aqueous detergent formulations. These carbon numbers can be reacted with benzene to make linear alkyl benzene (LAB), which can be further sulfonated to linear alkyl benzene sulfonate (LABS), a popular relatively low cost surfactant for household and industrial detergent applications.

Although some C₁₄ alpha olefin can be sold into aqueous detergent applications, C₁₄ has other applications such as being converted into chloroparaffins. A recent application of C₁₄ is as on-land drilling fluid base stock, replacing diesel or kerosene in that application. Although C₁₄ is more expensive than middle distillates, it has a significant advantage environmentally, being much more biodegradable and in handling the material, being much less irritating to skin and less toxic.

C₁₆-C₁₈ linear olefins find their primary application as the hydrophobes in oil-soluble surfactants and as lubricating fluids themselves. C₁₆-C₁₈ alpha or internal olefins are used as synthetic drilling fluid base for high value, primarily off-shore synthetic drilling fluids. The preferred materials for the synthetic drilling fluid application are linear internal olefins, which are primarily made by isomerizing linear alpha-olefins to an internal position. The higher internal olefins appear to form a more lubricious layer at the metal surface and are recognized as a better lubricant. Another application for C₁₆-C₁₈ olefins is in paper sizing. Linear alpha olefins are, once again, isomerized into linear internal olefins and are then reacted with maleic anhydride to make an alkyl succinic anhydride (ASA), a popular paper sizing chemical.

C₂₀-C₃₀ linear alpha olefins production capacity can be 5-10% of the total production of a linear alpha olefin plant. These are used in a number of reactive and non-reactive applications, including as feedstocks to make heavy linear alkyl benzene (LAB) and low molecular weight polymers used to enhance properties of waxes.

The use of 1-hexene can be as a comonomer in production of polyethylene. High-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) use approximately 2-4% and 8-10% of comonomers, respectively.

Another use of 1-hexene is the production of the linear aldehyde heptanal via hydroformylation (oxo synthesis). Heptanal can be converted to the short-chain fatty acid heptanoic acid or the alcohol heptanol

A more complete understanding of the components, processes, and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures (also referred to herein as “FIG.”) are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.

Turning now to FIG. 1 and FIG. 2, the pre-catalyst solutions can each be prepared in separate vessels 1, 10 equipped with continuous agitation/mixing to ensure homogenous mixing of catalyst components with a solvent, e.g., a hydrocarbon solvent. During preparation and storage of the pre-catalyst solutions, blanketing with an inert gas can be used to avoid ingress of moisture or air from the environment into the equipment.

The first pre-catalyst solution can be can be prepared separately, for example, batch-wise or in continuous mode, and then stored in a first vessel 1 at a temperature below the melting points of each component of the first pre-catalyst solution. The first pre-catalyst solution can include a first component 110, for example a modifier, and a second component 120, for example an organoaluminum compound, which can react in an exothermic reaction upon mixing when added to a solid catalyst preparation unit 5. The solid catalyst preparation unit 5 can include a heat removal mechanism to remove the heat of reaction. Heat generated from the combination of the organoaluminum compound with the modifier can be removed from the solid catalyst preparation unit 5. The first pre-catalyst solution can further include a first solvent 100. The first solvent 100 can be an aromatic or aliphatic solvent, or a combination comprising at least one of the foregoing. For example, the first solvent can be toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane, cyclohexane, olefins, such as hexene, heptane, octene, or ethers, such as diethylether or tetrahydrofurane. In an embodiment, the solvent can be an aromatic solvent.

The solid catalyst preparation unit 5 can be in fluid connection with a first vessel 1, for example the solid catalyst preparation unit 5 can be connected to the first vessel 1 with piping. The first pre-catalyst solution can flow from the solid catalyst preparation unit 5 to the first vessel 1. The first pre-catalyst solution can then be stored in the first vessel 1 for 1 hour to 90 days, for example, 1 hour to 7 days, for example, 1 hour to 72 hours. The first pre-catalyst solution can be circulated through a first pump 40 and a first cooler 50 and returned to the first vessel 1 wherein the first pre-catalyst solution can be maintained at a temperature of 0-50° C., for example, a temperature of 10-40° C., for example, 15-35° C. to sustain catalyst activity. The first pre-catalyst solution can be maintained at a pressure of 30 kiloPascals to 8000 kiloPascals, for example, 50 kiloPascals to 6000 kiloPascals, for example, 50 kiloPascals to 3500 kiloPascals within the first vessel 1.

The second pre-catalyst solution can be prepared separately, for example, batch-wise or in continuous mode, and then stored in a second vessel 10. The second pre-catalyst solution can include a third catalyst component 210, for example a ligand and a fourth catalyst component 220, for example chromium source in a second solvent 200. The second solvent 200 can be an aromatic or aliphatic solvent, or a combination comprising at least one of the foregoing. For example, the first solvent can be toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane, cyclohexane, olefins, such as hexene, heptane, octene, or ethers, such as diethylether or tetrahydrofurane. In an embodiment, the solvent can be an aromatic solvent. The second pre-catalyst solution can be stored in the second vessel 10 for 1 hour to 90 days, for example, 1 hour to 7 days, for example 1 to 72 hours. The second pre-catalyst solution can be circulated through a second pump 60 and a second cooler 70 and returned to the second vessel 10 wherein the second pre-catalyst solution can be maintained at a temperature of 0-50° C., for example, at a temperature of 10-40° C., for example, 15-35° C. to sustain catalyst activity. The second pre-catalyst solution can be maintained at a pressure of 30 kiloPascals to 8000 kiloPascals, for example, 50 kiloPascals to 6000 kiloPascals, for example, 50 kiloPascals to 3500 kiloPascals within the second vessel 10 of 10-50° C., for example, at a temperature of 15-25° C. to sustain catalyst activity.

After preparation, the first and second pre-catalyst solutions can be stored separately in a first vessel 1, and a second vessel 10, respectively, for further use in the process. The recirculation of the pre-catalyst solutions separately through pumps 40, 60 and coolers 50, 70, can assist in cooling and maintaining homogeneity of the stored pre-catalyst solutions.

The first pre-catalyst solution and the second pre-catalyst solution can be mixed in a catalyst preformation unit 12 to form a homogenous catalyst. In another aspect, the homogenous catalyst can be stored in the catalyst preformation unit 12 for up to 24 hours, for example, up to 6 hours, before use of the homogenous catalyst. The catalyst preformation unit 12 can be in fluid communication with a linear alpha olefin reactor 14, for example the catalyst preformation unit 12 can be connected to the linear alpha olefin reactor 14 with piping.

The accuracy and precision of dosed catalyst quantities can be ensured by proper design of conventional solid and liquid feeding systems. The final catalyst can be prepared by mixing the two pre-catalyst solutions either in a pipe or in a storage vessel, for example the catalyst preformation unit 12, at a pre-defined ratio. For example, the ratio of the first pre-catalyst solution to the second pre-catalyst solution can be 1:1, but a wider range is possible depending on the concentration of the stock solutions. For example, a molar ratio of the ligand/Cr is 0.5 to 50, for example, 0.8 to 2.0. A molar ratio of Al/Cr can be 1.0 to 1000, for example, 10 to 100. A molar ratio of the modifier/Cr can be 0.1 to 100, for example, 1 to 20. The residence time of the catalyst from the point where the two pre-catalyst solutions are mixed until the reactor can be based upon the catalyst shelf life, appropriate selection of pipe design and layout. The dosing of the homogenous catalyst into the reactor 14 can be flow-controlled. The homogenous catalyst can be injected either directly to the reactor 14 or into the hydrocarbon solvent feed upstream the reactor for better distribution inside the reactor 14.

Turning now to the catalyst, the various components of the catalyst are described in more detail.

(i) Chromium Compound

The chromium compound can be an organic salt, an inorganic salt, a coordination complex, or an organometallic complex of Cr(II) or Cr(III). In one embodiment, the chromium compound is an organometallic complex, preferably of Cr(II) or Cr(III). Examples of the chromium compounds include CrCl₃(tetrahydrofuran)₃, Cr(III)acetyl acetonate, Cr(III)octanoate, Cr(III)-2-ethylhexanoate, chromium hexacarbonyl, Cr(III)chloride, benzene(tricarbonyl)-chromium. A combination comprising at least one of the foregoing chromium compounds can be used.

The concentration of the chromium compound can vary depending on the particular compound used and the desired reaction rate. In some embodiments the concentration of the chromium compound is from about 0.01 to about 100 millimole per liter (mmol/l), about 0.01 to about 10 mmol/l, about 0.01 to about 1 mmol/l, about 0.1 to about 100 mmol/l, about 0.1 to about 10 mmol/l, about 0.1 to about 1.0 mmol/l, about 1 to about 10 mmol/l, and about 1 to about 100 mmol/l. Preferably, the concentration of the chromium compound is from about 0.1 to about 1.0 mmol/l, most preferably, about 0.5 to about 0.6 mmol/L.

(ii) Ligand

The ligand can be a PNPNH ligand. The ligand can have the backbone PNPNH, which as used herein has the general structure R¹R²P—N(R³)—P(R⁴)—N(R⁵)—H wherein each of R¹, R², R³, R⁴, and R⁵ is independently a hydrogen, halogen, C₁₋₁₈ hydrocarbyl group, amino group of the formula NR^(a)R^(b) wherein each of R^(a) and R^(b) is independently hydrogen or a C₁₋₁₈ hydrocarbyl group, a silyl group of the formula SiR^(a)R^(b)R^(c) wherein each of R^(a), R^(b), and R^(c) is independently hydrogen or a C₁₋₁₈ hydrocarbyl group, or two of R¹, R², R³, R⁴, R⁵, R^(a), or R^(b) taken together are a substituted or unsubstituted C₁₋₁₀ hydrocarbylene group linked to the same or different heteroatoms to form a heterocyclic structure. Exemplary ligands having a heterocyclic structure include the following

wherein R¹, R², R³, R⁴, R⁵ are as described above. In a specific embodiment, each R¹, R², R³, R⁴, R⁵ are independently hydrogen, substituted or unsubstituted C₁-C₈ alkyl, substituted or unsubstituted C₆-C₂₀ aryl, more preferably unsubstituted C₁-C₆ alkyl or unsubstituted C₆-C₁₀ aryl. A specific example of the ligand is (phenyl)₂PN(iso-propyl)P(phenyl)N(iso-propyl)H, commonly abbreviated Ph₂PN(i-Pr)P(Ph)NH(i-Pr).

The molar ratio of ligand/Cr can be 0.5 to 50, 0.5 to 5, 0.8 to 2.0, 1.0 to 5.0, or 1.0 to 1.5.

(iii) Modifier

The modifier can be selected from ethers, anhydrides, amines, amides, quaternary ammonium salts, silicates, silyl ethers, siloxanes, esters, carbonates, ureas, carbamates, sulfoxides, sulfones, phosphoramides, silanes, acetals, or a combination comprising at least one of the foregoing. For example, the modifier can be selected from ammonium or phosphonium salts of the type [H₄E]X, [H₃ER]X, [H₂ER₂]X, [HER₃]X or [ER₄]X or HX or RX with E=N or P, X═Cl, Br or I and R=alkyl, cycloalkyl, acyl, aryl, alkenyl, alkynyl or the corresponding bridging di-, tri- or multiunits, or ammonium or phosphonium salts based on cyclic amines, or a combination comprising at least one of the foregoing. The modifier can be present in a concentration amount of 0.1 to 15 mmol/L, for example, 0.3 to 0.5 mmol/L.

(iv) Solvents

The catalyst composition can further contain one or two solvents, e.g., hydrocarbon solvents. Exemplary solvents are an aromatic or aliphatic solvent, or a combination comprising at least one of the foregoing. For example, the first solvent can be toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane, cyclohexane, olefins, such as hexene, heptane, octene, or ethers, such as diethylether or tetrahydrofurane. In an embodiment, the solvent can be an aromatic solvent, for example, toluene.

(v) Organoaluminum Compound

The organoaluminum compound can be methylaluminoxane (MAO), modified methylaluminoxane (MMAO), ethylaluminum sesquichloride (EASC), diethylaluminum chloride (DEAC), trialkylaluminum, e.g., trimethylaluminum or triethylaluminium, isobutylealuminoxane (IBAO), tri-isobutyl aluminum (TIBA). A combination comprising at least one of the foregoing chromium compounds can be used. The organoaluminum compound can be present in a concentration amount of 0.24 to 2400 mmol/L, for example, 6 to 8 mmol/L.

The homogenous catalyst composition disclosed herein can be used in a process for the oligomerization of ethylene. Those skilled in the art will understand that oligomerization of ethylene to produce 1-hexene can be by trimerization of ethylene, and oligomerization of ethylene to produce 1-octene can be by tetramerization of ethylene. In an embodiment, the process encompasses contacting ethylene with the catalyst composition under ethylene oligomerization conditions effective to produce 1-hexene and/or 1-octene.

The oligomerization of ethylene can be carried out at a pressure of about 0.1 MegaPascals (MPa) to about 20 (MPa), about 1 MPa to about 20 MPa, about 1 MPa to about 10 MPa, about 2 MPa to about 7 MPa, and about 1 MPa to about 5 MPa. Desirably, the oligomerization is at a pressure of about 2 MPa to about 7 MPa.

The oligomerization of ethylene can also be performed at a temperature of from about 10 to about 200° C., about 20 to about 100° C., about 30 to about 100° C., about 40 to about 100° C., about 40 to about 80° C., preferably about 40 to about 70° C.

The process can be carried out continuously, semi-continuously or discontinuously.

The process is usually carried out in a reactor. The time it takes for the process to be carried out, usually in the reactor, is also known as residence time. The mean residence time of the process may be from about 10 minutes to about 20 hours, about 20 minutes to about 20 hours, about 1 hour to about 16 hours, about 1 hour to about 8 hours, preferably about 1 to about 4 hours.

For disposal of the homogenous catalyst (i.e. during operational upset) the catalyst stream can be mixed with the deactivation agent and then transferred as waste. After disposal of the catalyst solution as waste, the associated piping can be flushed by a hydrocarbon solvent for washing purposes.

The methods disclosed herein include at least the following aspects:

Aspect 1: A method for preparing a homogenous catalyst for the production of linear alpha olefins, comprising: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel for a period of time of 1 hour to 90 days; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel for a period of time of 1 hour to 90 days; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst pre-formation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the homogenous catalyst.

Aspect 2: The method of Aspect 1, wherein the chromium source is selected from organic or inorganic salts, coordinate complexes and organometallic complexes of Cr(II) or Cr(III), preferably CrCl₃(THF)₃, CR(III) acetyl acetonate, Cr(III) octanoate, chromium hexacarbonyl, Cr(III)-2-ethylenexanoate, benzene(tricarbonyl)-chromium, Cr(III) chloride, or a combination comprising at least one of the foregoing.

Aspect 3: The method of any of the preceding aspects, wherein the ligand has has the general structure R₁R₂P—N(R₃)—P(R₄)—N(R₅)—H, wherein R₁, R₂, R₃, R₄ and R₅ are independently selected from halogen, amino, trimethylsilyl, C₁-C₁₀-alkyl, substituted C₁-C₁₀-alkyl, aryl and substituted aryle.

Aspect 4: The method of any of the preceding aspects, modifier is selected from ammonium or phosphonium salts of the type [H₄E]X, [H₃ER]X, [H₂ER₂]X, [HER₃]X or [ER₄]X or HX or RX with E=N or P, X═Cl, Br or I and R=alkyl, cycloalkyl, acyl, aryl, alkenyl, alkynyl or the corresponding bridging di-, tri- or multiunits, or ammonium or phosphonium salts based on cyclic amines, or a combination comprising at least one of the foregoing.

Aspect 5: The method of any of the preceding aspects, wherein the organoaluminum compound includes methylaluminoxane (MAO), trialkyaluminum, preferably, tri-isobutyl aluminum or isobutyl aluminoxane, or a combination comprising at least one of the foregoing.

Aspect 6: The method of any of the preceding aspects, wherein the first solvent and second solvent independently include an aromatic or aliphatic solvent, or a combination comprising at least one of the foregoing, preferably toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane, cyclohexane, olefins, such as hexene, heptane, octene, or ethers, such as diethylether or tetrahydrofurane, more preferably an aromatic solvent.

Aspect 7: The method of any of the preceding aspects, further comprising removing heat generated from the combination of the organoaluminum compound with the modifier from the first vessel.

Aspect 8: The method of any of the preceding aspects, wherein the first vessel, the second vessel, and the reaction vessel are maintained under an inert gas environment.

Aspect 9: The method of any of the preceding aspects, wherein the first pre-catalyst solution in the first vessel is circulated through a first pump and a first cooler, and returned to the first vessel, wherein the first pre-catalyst solution is maintained at a temperature of 0-50° C., preferably, 10-40° C., more preferably 15-35° C.

Aspect 10: The method of any of any of the preceding aspects, wherein the second pre-catalyst solution in the second vessel is circulated through a second pump and a second cooler, and returned to the second vessel, wherein the second pre-catalyst solution is maintained at a temperature of 0-50° C., preferably, 10-40° C., more preferably 15-35° C.

Aspect 11: The method of any of the preceding aspects, wherein the first pre-catalyst solution is stored in the first vessel for a period of time of 1 hour to 7 days, preferably 1 hour to 72 hours.

Aspect 12: The method of any of the preceding aspects, wherein the second pre-catalyst solution is stored in the second vessel for a period of time of 1 hour to 7 days, preferably 1 hour to 72 hours.

Aspect 13: The method of any of the preceding aspects, wherein the first pre-catalyst solution and the second pre-catalyst solution are added directly to the reaction vessel.

Aspect 14: The method of any of the preceding aspects, wherein the first pre-catalyst solution and the second pre-catalyst solution are added to a hydrocarbon solvent feed upstream from the reaction vessel.

Aspect 15: The method of any of the preceding aspects, further comprising sustaining the temperature of the homogenous catalyst at 10-50° C., preferably at 15-25° C. to sustain catalytic activity.

Aspect 16: A homogenous catalyst prepared by any methods of any of the preceding aspects.

Aspect 17: The method of any of the preceding aspects, wherein the homogeneous catalyst is stored in the reaction vessel for up to 24 hours prior to contact with the alpha olefin.

Aspect 18: The method of any of the preceding aspects, wherein the alpha olefin includes ethylene.

Aspect 19: The method of any of the preceding aspects, wherein the linear alpha olefin includes 1-butene and/or 1-hexene.

Aspect 20: The method of any of the preceding aspects, wherein prior to contacting the homogenous catalyst with an alpha olefin, the homogenous catalyst is added to a solvent feed stream upstream from a reaction vessel containing the alpha olefin.

In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The invention may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of “less than or equal to 25 wt %, or 5 wt % to 20 wt %,” is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. “Combination” is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to denote one element from another. The terms “a” and “an” and “the” herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or.” The suffix “(s)” as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the film(s) includes one or more films). Reference throughout the specification to “one embodiment”, “another embodiment”, “an embodiment”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). The notation “±10%” means that the indicated measurement can be from an amount that is minus 10% to an amount that is plus 10% of the stated value. The terms “front”, “back”, “bottom”, and/or “top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. “Optional” or “optionally” means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A “combination” is inclusive of blends, mixtures, alloys, reaction products, and the like.

Unless otherwise specified herein, any reference to standards, regulations, testing methods and the like, such as ASTM D1003, ASTM D4935, ASTM 1746, FCC part 18, CISPR11, and CISPR 19 refer to the standard, regulation, guidance or method that is in force at the time of filing of the present application.

As used herein, the term “hydrocarbyl” and “hydrocarbon” refers broadly to a substituent comprising carbon and hydrogen, optionally with 1 to 3 heteroatoms, for example, oxygen, nitrogen, halogen, silicon, sulfur, or a combination thereof; “alkyl” refers to a straight or branched chain, saturated monovalent hydrocarbon group; “alkylene” refers to a straight or branched chain, saturated, divalent hydrocarbon group; “alkylidene” refers to a straight or branched chain, saturated divalent hydrocarbon group, with both valences on a single common carbon atom; “alkenyl” refers to a straight or branched chain monovalent hydrocarbon group having at least two carbons joined by a carbon-carbon double bond; “cycloalkyl” refers to a non-aromatic monovalent monocyclic or multicylic hydrocarbon group having at least three carbon atoms, “cycloalkenyl” refers to a non-aromatic cyclic divalent hydrocarbon group having at least three carbon atoms, with at least one degree of unsaturation; “aryl” refers to an aromatic monovalent group containing only carbon in the aromatic ring or rings; “arylene” refers to an aromatic divalent group containing only carbon in the aromatic ring or rings; “alkylaryl” refers to an aryl group that has been substituted with an alkyl group as defined above, with 4-methylphenyl being an exemplary alkylaryl group; “arylalkyl” refers to an alkyl group that has been substituted with an aryl group as defined above, with benzyl being an exemplary arylalkyl group; “acyl” refers to an alkyl group as defined above with the indicated number of carbon atoms attached through a carbonyl carbon bridge (—C(═O)—); “alkoxy” refers to an alkyl group as defined above with the indicated number of carbon atoms attached through an oxygen bridge (—O—); and “aryloxy” refers to an aryl group as defined above with the indicated number of carbon atoms attached through an oxygen bridge (—O—).

Unless otherwise indicated, each of the foregoing groups can be unsubstituted or substituted, provided that the substitution does not significantly adversely affect synthesis, stability, or use of the compound. The term “substituted” as used herein means that at least one hydrogen on the designated atom or group is replaced with another group, provided that the designated atom's normal valence is not exceeded. When the substituent is oxo (i.e., ═O), then two hydrogens on the atom are replaced. Combinations of substituents and/or variables are permissible provided that the substitutions do not significantly adversely affect synthesis or use of the compound. Exemplary groups that can be present on a “substituted” position include, but are not limited to, cyano; hydroxyl; nitro; azido; alkanoyl (such as a C₂₋₆ alkanoyl group such as acyl); carboxamido; C₁₋₆ or C₁₋₃ alkyl, cycloalkyl, alkenyl, and alkynyl (including groups having at least one unsaturated linkages and from 2 to 8, or 2 to 6 carbon atoms); C₁₋₆ or C₁₋₃ alkoxys; C₆₋₁₀ aryloxy such as phenoxy; C₁₋₆ alkylthio; C₁₋₆ or C₁₋₃ alkylsulfinyl; C1-6 or C₁₋₃ alkylsulfonyl; aminodi(C₁₋₆ or C₁₋₃)alkyl; C₆₋₁₂ aryl having at least one aromatic rings (e.g., phenyl, biphenyl, naphthyl, or the like, each ring either substituted or unsubstituted aromatic); C₇₋₁₉ arylalkyl having 1 to 3 separate or fused rings and from 6 to 18 ring carbon atoms; or arylalkoxy having 1 to 3 separate or fused rings and from 6 to 18 ring carbon atoms, with benzyloxy being an exemplary arylalkoxy.

All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents. 

What is claimed is:
 1. A method for preparing a homogenous catalyst for the production of linear alpha olefins, comprising: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst preformation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the alpha olefin; wherein the first pre-catalyst solution in the first vessel is circulated through a first pump and a first cooler, and returned to the first vessel, wherein the first pre-catalyst solution is maintained at a temperature of 0-50° C.
 2. The method of claim 1, wherein the chromium source is selected from organic or inorganic salts, coordinate complexes and organometallic complexes of Cr(II) or C(III) or a combination comprising at least one of the foregoing.
 3. The method of claim 1, wherein the ligand has the general structure R₁R₂P—N(R₃)—(R₄)—N(R₅)—H, wherein R₁, R₂, R₃, R₄ and R₅ are independently selected from halogen, amino, trimethylsilyl, C₁-C₁₀-alkyl, substituted C₁-C₁₀-alkyl, aryl and substituted aryl.
 4. The method of claim 1, wherein the modifier is selected from ammonium or phosphonium salts of the type [H₄E]X, [H₃ER]X, [H₂ER₂]X, [HER₃]X or [ER₄]X or HX or RX with E=N or P, X═CI, Br or I and R=alkyl, cycloalkyl, acyl, aryl, alkenyl, alkynyl or the corresponding bridging di-, tri- or multiunits, or ammonium or phosphonium salts based on cyclic amines, or a combination comprising at least one of the foregoing.
 5. The method of claim 1, wherein the organoaluminum compound includes methylaluminoxane or trialkylaluminum, or a combination comprising at least one of the foregoing; and wherein the first solvent and second solvent independently include an aromatic or aliphatic solvent, or a combination comprising at least one of the foregoing.
 6. The method of claim 5, wherein the aromatic or aliphatic solvent is selected from the group consisting of toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane, cyclohexane, an olefin and an ether.
 7. The method of claim 5, wherein the solvent is an aromatic solvent selected from the group consisting of toluene, benzene, ethylbenzene, cumenene, xylene, mesitylene, hexane, octane and cyclohexane.
 8. The method of claim 1, wherein the first vessel, the second vessel, and the reaction vessel are maintained under an inert gas environment.
 9. The method of any of claim 1, wherein the second pre-catalyst solution in the second vessel is recirculated through a second pump and a second cooler, and returned to the second vessel, wherein the second pre-catalyst solution is maintained at a temperature of 0-50° C.
 10. The method of claim 1, wherein the first pre-catalyst solution is stored in the first vessel for a period of time of 1 hour to 7 days.
 11. The method of claim 1, wherein the second pre-catalyst solution is stored in the second vessel for a period of time of 1 hour to 7 days.
 12. The method of claim 1, further comprising sustaining the temperature of the homogenous catalyst at 10-50° C. to sustain catalytic activity.
 13. The method of claim 1, wherein the homogeneous catalyst is stored in the reaction vessel for up to 24 hours prior to contact with the alpha olefin.
 14. The method of claim 1, wherein the alpha olefin includes ethylene.
 15. The method of claim 1, wherein the linear alpha olefin includes 1-butene and/or 1-hexene.
 16. The method of claim 1, wherein prior to contacting the homogenous catalyst with an alpha olefin, the homogenous catalyst is added to a solvent feed stream upstream from a reaction vessel containing the alpha olefin.
 17. A method for preparing a homogenous catalyst for the production of linear alpha olefins, comprising: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel for a period of time of 1 hour to 90 days; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel for a period of time of 1 hour to 90 days; and after the period of time of 1 hour to 90 days, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time of 1 hour to 90 days, adding the second pre-catalyst solution to the catalyst pre-formation unit; forming a homogenous catalyst by mixing the first pre-catalyst solution and the second pre-catalyst solution; adding the homogeneous catalyst to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the homogeneous catalyst and the alpha olefin, wherein the first pre-catalyst solution in the first vessel is circulated through a first pump and a first cooler, and returned to the first vessel, wherein the first pre-catalyst solution is maintained at a temperature of 0-50° C.
 18. A method for preparing a homogenous catalyst for the production of linear alpha olefins, comprising: preparing a first pre-catalyst solution comprising a modifier and an organoaluminum compound in a first solvent wherein the first pre-catalyst solution is reacted and stored in a first vessel; preparing a second pre-catalyst solution comprising a second solvent, a ligand, and a chromium containing compound, wherein the second pre-catalyst solution is stored in a second vessel; and after a period of time, adding the first pre-catalyst solution to a catalyst pre-formation unit; after the same period of time, adding the second pre-catalyst solution to the catalyst preformation unit; adding the first pre-catalyst solution and the second pre-catalyst solution to a hydrocarbon solvent feed to form a feed solution; adding the feed solution to a reaction vessel, wherein the reaction vessel comprises an alpha olefin; and forming the linear alpha olefin by mixing the feed solution with the alpha olefin.
 19. The method of claim 18, wherein the time period is from 1 hour to 90 days. 